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a(1) = 9; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n). Alternate left and right concatenation yielding primes.
9

%I #2 Dec 05 2013 19:55:16

%S 9,97,197,1973,31973,319733,3319733,331973311,6331973311,633197331131,

%T 5633197331131,563319733113127,6563319733113127,65633197331131279,

%U 3465633197331131279,346563319733113127933,18346563319733113127933

%N a(1) = 9; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n). Alternate left and right concatenation yielding primes.

%e a(4) = 1973 staring with a(3) =197 and a(5) = 31973 ending in a(4) = 1973.

%Y Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617, A069618, A069619, A069620.

%K nonn,base

%O 1,1

%A _Amarnath Murthy_, Mar 27 2002

%E More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003